My dad is wanting to play a flight simulator and is having some problems running it do to his integrated video card. I am not much of a computer techie but I think his video runs off of his mother board? He is running a Dell G75692. Here is the specs!

If someone could tell me the type of video cards that he could install I would greatly appreciate it. I am just not sure if its a PCI express, PCI express x 1, PCI express 2.0 x 16, PCI express 2.1 x 16 etc........ Could someone also explain to me what PCI express means if you don't mind? I really appreciate you helping us out! Here is the requirements for the game: